This particular invention has application to the so-called skid-steer loaders which are equipped with loader arms that pivotally attach to a loader bucket near the bottom of the bucket and there is a cylinder assembly pivotally connected between the arm and the bucket for pivoting the bucket in the loading and emptying of the bucket. A common arrangement of the prior art loaders is such that the location of the pivot point of the cylinder assembly and the bucket is at a higher elevation than the location of the pivot point between the arm and the bucket. With that arrangement, the cylinder assemblies are generally mounted between the loader arms or on top of the loader arms, and the break-out and roll-back of the bucket is achieved with the rod ends of the cylinder assemblies. As such, the cylinder assemblies are exposed and are therefore subject to damage from being bumped and also from the material spilling over the back of the bucket onto the cylinder assemblies.
The prior art also has the so-called reverse linkage wherein the pivot connection between the bucket and the cylinder assembly is at an elevation lower than the location of the pivot connection between the arm and the bucket, at least when the bucket is in the normal horizontal loading position. Prior art examples of utilization of cylinder assemblies with loader buckets and the like are found in U.S. Pat. Nos. 3,239,083 and 3,251,490 and 3,554,396 and 3,610,450 and 3,612,311. These patents show loader buckets or the like with cylinder assemblies attached at points which are lower than the elevation of the attachment location between the bucket and the arm. However, the aforesaid patents all reveal that the cylinder assembly is exposed at a location directly rearwardly of the bucket or the like, and thus it is subject to being damaged and to having the loading material fall onto the cylinder assembly.
Accordingly, the present invention utilizes an arrangement wherein the cylinder assembly is enclosed and thus is protected from damage and from material which spills over the back of the bucket, and this is accomplished by providing a hollow loader or lift arm and placing the cylinder assembly within the hollow arm. The prior art is aware of some arrangement for somewhat nesting a cylinder assembly in loader buckets or like implements, and that partial nesting is shown in U.S. Pat. Nos. 2,645,368 and 3,042,233 and 3,061,123 and 3,184,085 and 3,666,124 and 3,695,467 and 3,698,580 and 4,015,728. Thus, these patents show cylinder assemblies used with loader buckets or the like and with the assembly being somewhat concealed by or partially nested within the lift arm or the like. However, these patents do not show a loader or lift arm which is completely enclosed around its transverse girth and has a hollow interior extending along the axis thereof and terminating in an open end adjacent the bucket or the like.
The present invention combines the use of the reverse linkage and the enclosed cylinder assembly and presents several important and basic advantages. One advantage is that the cylinder assembly is pressurized at its head end during the break-out and rollback actions, and this increases the force applied during these actions and by a given capacity cylinder assembly. Additionally, the cylinder assembly is enclosed and is not subject to damage by being bumped or by material spilling thereon from the bucket. Still further, the enclosed cylinder assemblies are thus out of the way and do not protrude to obscure the operator vision of the work area or to obstruct the entry to the tractor, and they are out of the way and therefore provide for greater maneuverability of the loader arms. Still further, with the reverse linkage and the enclosed cylinder assemblies, the overall length of the machine can be reduced, and also the degree of articulation of the bucket on the arms is an optimum, and the bucket can be maneuvered in maximum scooping action to provide for a self-filling function of the bucket. Further, since the head end of the cylinder is pressurized during bucket loading, the loading action is not only more forcefully accomplished but it is more slowly and accurately accomplished with greater control, and, conversely, during dumping of the bucket, the reverse linkage arrangement provides for a more rapid dump action, and that rapid action will help to shake material from the bucket as well as increase productivity.
In summary, the present invention provides for an assembly of a loader arm and a bucket and a cylinder assembly all of which constitutes a reverse linkage connection and with the cylinder assembly concealed within the hollow loader arm and with it arranged so that maximum force can be applied by the cylinder assembly in the loading of the bucket and maximum speed in the dumping action can be achieved. In this accomplishment, the cylinder assembly is protected from damage and debris and it is out of the way both for maneuverability of the arms and for the operators's view of the work area and for access to other parts of the machine, and yet the assembly is connected directly to the bucket and no intervening linkages are required.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.